Four X Doctor Dana 30 Front Diff Guard
Both Jacquie and I took pretty good wacks at the front differential cover. I can't remember who won (whose dent was the biggest), but hitting it twice in a row was enough to start us looking for a diff guard.
I looked at guards from Rocky Road Outfitters (formerly Summit Offroad) and Four X Doctor. See images of them below. Both looked like they would provide adequate protection, but I preferred the Four X Doctor design. As the Four X Doctor description says, their diff guards "are designed to help you slide up and over rocks and debris, instead of just taking a hit straight into the cover and stopping the vehicle."
I was fortunate enough to have Will, a fellow SLO Four Wheeler, sell me his unused guard minus the normally included longer bolts. I placed a quick call to the Four X Doctor who told me I needed five 5/16" x 3/4" Grade 5 bolts and washers. Incidentally, Grade 5 bolts can be identified by three equally spaced radial lines stamped into the bolt head; Grade 2 have no marks and Grade 8 bolts (too strong for our application) have six marks.
A word about color: The Four X Doctor guards are shipped black. Mine is silver because the previous owner powder coated it, presumably to match his chromed diff cover. The Four X Doctor web site shows the guard blue, but only so that the part stands out against the black diff cover.)
Installing the Diff Guard
Remove the five bolts (or however many bolts your type diff has). You can safely remove the bolts without the gear oil--nasty, smelly stuff--leaking out if your cover is installed correctly. The remaining top bolts and the sealant should be sufficient to prevent any spills.
Be sure to test fit the guard. I have read differerent accounts of this installation... some guards fit perfectly, some have had to be trimmed to fit. I don't know about my diff because Will had already trimmed the guard to fit his diff cover. In any case, the pre-trimmed guard fit perfectly.
Install and tighten the bolts and washers (see torque.htm). You are done.
Bolt grade image source: http://www.unified-eng.com/scitech/bolt/boltmarks.html
